Safety-catch mechanism



ll- I8 April 7, 1931.

w. c. DE Roo 1,799,358

SAFETY CATCH MECHANISM Filed Sept, 9, 1927 Mimi? e R00,

fiiisni such as is used in machine tools and' Patented Apr. 7, A1931 fri-'reino STATE. s

WILLIAM C. DE noo, Aor CINCINNATI,l OHIO, AssIGNoB. Torna rosDiCK MACHINE Toor.

COMPANY,l or CINCINNATI, lomofeg cortroniirioN or oiaIIo yf s ArETYoATCIIzMnCnANisM ilse in connection. with an' elevating mechasafety catchadapted. to be carried by a rotatable nut which co-operates with a iiXed elevating 4screw for raising and lowering a drill-head, radial drill alim of a machine tool.

. Another object'is'to'provide'a safety catch or similar part of the type referred: to which has normallyl anonbearing relation with its `associated parts but which, .immediately `upon breakage of the threads in the elevating nutyassumes aii'operative connection with the leadn screw andftlien stopsdescent of the head or yarm .with which *itl is connected.

Another object is to provideA a safety catch of this kind which isineXpensive to manufacture and which furthermore is automatic in function. x n

' These and other objects are attainedby the incansdescribed vherein and disclosed in the accompanying drawings, in which Fig. 1 is a fraginental elevational view of` a device having embodied therein the safety i catch of the invention.4 l

y ',Fig. 2is,a`cross sectionalfview taken on .line 2 2 of Fig. 1. i

Figf is a fragmental cross 'section taken online 3-3 of Fig. 1^.

Fig. 4 is a view taken outline 4 4 of Fig. v

\ 2, showing, infullflinesthe catch of the invention. operatively positioned to arrest descent rof a drill arm. Y Y v Iii the present embodiment the device of the invention is applied to the armof a lradial drill press wherein the usual column 6 andv fixed elevating screw 7 have associated therewith radial larm 8. 'An elevating nut 9 en-vf,l gages the fix-ed screw 7 and is adapted to be power driven through a gear 10 meshing with a' gear 11 fixed to the nut. The gear 10 receives its power from a suitable transmission which is controlled in thisy embodiment. by a friction clutch 12. The body of the nut 9 has a longitudinal slot 13 which extends radially through the body of the nut atthe y ylower end thereof. The safety catch 14 is This vinvention relates to a 'safety catch for vArplrilcatoii filed Septniber9,`1927. Sera1-No. 218,560. Y

p ivotally mounted ena-pin ,15 which extends the threads on tlieelevating screw, but lwhich normally have no bearing thereon. `Thusit 'will beseeii that the catch 14 can not, rotate about its bearing onA the pin 15 except inthe event of bodily non-rotating descent of `the elevating nut relative to the screw. yAn in-` tegral 1ug18 onthe catch 14 projects beyond the periphery of the tooth :portion and under normal conditions remains vertical.` The ing 19 which incasesthe elevating nut 9 and 'its bearing, the cylindrical Wall 20-beiiig cut awayto provide an' opening bounded by vertical edges 21 and 22 of the wall 20. -Basef23 of housing 19 is disposed. closely adjacent the bottom of the elevating `nut 9. l vThe odge 22 constitutes abutment against which the rlug 18 of the safety-catch may engage when,

upon failure of threaded engagement, the nut begins bodily non-rotating descent .,oi'i the screw. At such times the teeth on edge lfo'fiu 14 with lug 18-is atthis. moment rtending to rotate Von its axis, but is yprecluded from doing so bytheviniiei' face of wallV 2O until tlie lug has cleared the edge 21iofthe opening. Thelug 18 being then freed of resistance, the

catchwill make a one-quarter turn on its `axis. f and will be projected vthrough the opening and assume an outwardly.extending horizon- 4varm 8 has a substantially-cylindrical houstal position. It willthen be carried by the nut against the abutment edge 22 which foriiis a lwall of the opening through which the catch has just been projected. `This stops furf ther movement of the nutandholds the head against descent. It willbe noted that under no circumstances will there be more than a Vportion lof'one revolution of; the nutbetweeirf. `'the failure of kthreaded engagement and they locking thereof by the vcatch againsttheabutment. v y

The operation ofthe device'isas follows:

l/Vhen the threads on elevating .nut 9 arefiiijl at theleft of Fig. `2,.namely lwith the lug 18 in upright position. As the nut is Arota-ted the safet catch 14 travels bodily with .the nut and t e teeth on the catch have no actual bearing on the vscrew 7 although the catch is precluded from turning about its axis by reason of such teeth extending between the threads on the elevating screw 7. Assuming that the threads on the-*elevating nut `9 have 4 become badly worn after a long period of use and should break either whilethe ma- Y vthe combination with suoli arm, a nut revoluchine is in-operation or at any other time, the tendency willvbe forthe arm 8 to'V drop. As soon as the engagement of the threads on the nut 9 with threads on screw 7 fails, the teeth on catch 14engage with the threads on the screw thereby tending 'to rotate the catch about its pivotal mounting. The inner face of the wall .20 will preclude such movement until the catch 14 passes beyond theedge 21 lof the Wall. The catch willnow rotate about its axis as the arm moves downwardly so that the lug will project outwardly beyond the edge 21 'ofwall 2O whereupon the catch ywill move through a short arc into abutment with the edge 22on the opposite side of the opening in the wall. the nut against further' movement, and should it be under power at the time, friction vclutch 12 will slip so that no damage tothe parts results. At this time the catch is in the position shown in dot-ted lines at the right hand side of Fig. 2. The device remains locked against further elevating or lowering of the arm until the machine is repaired thus precluding the possibility of injury to one who mightendeavor to operate the machine prior to its repair.

What is claimed is 1. In a jdevice of :the class described the combination of a vertically movable member,

`a fixed elevating screw, a nut revolubly mounted on the movable member whereby sald member is ralsed and lowered on the screw, a ysafety catch pivotally mounted inl the/nut and vhaving teeth lthereon meshed'in normally non-'bearingfrelation with the screw, said catch being lmovable Vabout its pivotal mounting to project beyond the bodyofthe nut upon abnormal longitudinal movement of the vnut over the screw, an-d'me'ans on the movable member adapted to precludev rotation of the ynut when the catch is in the last mentioned position.`

This abutment locks to be raised and lowered on the screw, a nut on the screw and revolubly mounted on the member, an abutment on said member adjacent thenut, and a pivotally'mounted catch v adapted to be mov-ed about its pivotal mounting against the abutment upon failure of threaded engagement of the nut and screw,

whereby to hold the nut against rotation.

4.fIn a safety device for .a radial drill arm blymounted in thearm, aXed screw threaded in the nut for supporting the arm,a catch pivotally mounted inthe `nut and vhaving a geared portion in normally non-bearing engagement with the screw whereby vupon breakage of thethreads on thenut, the geared portion of the catch may engage in bearing relation with the screw for `moving thefcatch about its pivotal mounting into abutment with the `body of the Aarm whereby'the nut is locked against further .rotation and the arm is flocked against movement relative to the screw. Y 1

A5. In a device of the class described a fixed non-rotating screw, a member adapted for movement longitudinally of the screw, a nut on` the screw and rotatably mounted in the member, and a catch journalled `on the nut adapted to become operative 4upon failure ,of threaded engagement of the nut and screw to preclude Arotation of the-nut and tozengage the screw and member :for Aprecluding movement of said member relative tothe screw.

6. In a safety device anon-rotating screw, a nut on the screw, a catch j ournalled on the nut adapted to engage the threads on the screw upon failure of threaded cofoperation between the nut and screw and .means co-operating with the catch whenfin the last finentioned position to arrest relative movement of the nut and screw.

In testimony whereof, Ifhave hereuntosubscripedmy name this l2nd day of September, 192 l VI-LL'IAM 1C. DE ROO.

2. In a device of the class describedthe Ycombination of a'ixed screw, a movable member, a nut associated withthe movable member and rotatable for effecting raising and v:lowering of the -movable 'member on the screw, atoothed catch pivotally mounted on 

